The use of virtualization is becoming widespread. Virtualization describes a software abstraction that separates a computer resource and its use from an underlying physical device. Generally, a virtual machine (VM) provides a software execution environment and may have a virtual processor, virtual system memory, virtual storage, and various virtual devices. Virtual machines have the ability to accomplish tasks independently of particular hardware implementations or configurations.
Virtualization permits multiplexing of an underlying host machine (associated with a physical CPU) between different virtual machines. The host machine or “host” allocates a certain amount of its resources to each of the virtual machines. Each virtual machine may then use the allocated resources to execute applications, including operating systems (referred to as guest operating systems (OS) of a “guest”). The software layer providing the virtualization is commonly referred to as a hypervisor and is also known as a virtual machine monitor (VMM). The hypervisor emulates the underlying hardware of the virtual machine, making the use of the virtual machine transparent to the guest operating system and the user of the VM.